@include describe('kf-stagger') {
  @include it('Properly staggers animations with negative deltas') {
    $input: (
      ('.a': (background: (0ms: red, 2000ms: green))),
      ('.b': (background: (0ms: blue, 1000ms: purple))),
      ('.c': (background: (0ms: black, 1500ms: white))),
    );
    $expected-output: (
      ".a": (background: (0ms: red, 2000ms: green)),
      ".b": (background: (1500ms: blue, 2500ms: purple)),
      ".c": (background: (2000ms: black, 3500ms: white)),
      _kf-map-type: eptv,
      _kf-duration: 3500ms,
    );

    @include assert-equal(
      kf-stagger(-500ms, $input...),
      $expected-output
    );
  }

  @include it('Properly staggers animations with positive iterator') {
    $input: (
      ('.a': (background: (0ms: red, 50ms: green))),
      ('.b': (background: (0ms: blue, 50ms: purple))),
      ('.c': (background: (0ms: a, 100ms: b))),
      ('.d': (background: (0ms: c, 100ms: d))),
      ('.e': (background: (0ms: e, 100ms: f))),
      ('.f': (background: (0ms: g, 100ms: h))),
    );
    $expected-output: (
      ".a": (background: (0ms: red, 50ms: green)),
      ".b": (background: (550ms: blue, 600ms: purple)),
      ".c": (background: (1100ms: a, 1200ms: b)),
      ".d": (background: (1700ms: c, 1800ms: d)),
      ".e": (background: (2300ms: e, 2400ms: f)),
      ".f": (background: (2900ms: g, 3000ms: h)),
      _kf-map-type: eptv,
      _kf-duration: 3000ms,
    );

    @include assert-equal(
      kf-stagger(500ms, $input...),
      $expected-output
    );
  }
}